A key method to gain access to ETDs is through browsing. Browsing promotes serendipity, in analogous fashion to when a person looks around in library stacks, picking up and glancing at a number of works, typically ones that are relatively close to each other.
Browsing often involves a researcher in a learning process connecting with the concepts, areas, and vocabulary used in a particular field. A researchers often moves around in "concept space", seeing what concepts are broader and which are narrower, which are related, and which are examples or applications of theories or methods. Thus, in the case of medical works, browsing often encourages researchers to think about diseases, treatments, location in an organism (or human body or subsystem thereof), symptoms, and other considerations. In many fields, browsing involves exploring a taxonomic system, managing an organization chart or hierarchical structure, or moving from a term to a more focused noun phrase.
In many disciplines, there are official classification systems. Some are quite broad, in some cases covering all areas, as is the case when using the subject headings prepared by the US Library of Congress (LCSH), or the Dewey Decimal Classification system (DDC, available from Forest Press, owned by OCLC). However, for in-depth characterization of a research work in a particular field, it is more appropriate to use the category system for the field. In computing, the ACM system is popular. In medicine, MeSH or UMLS are widely used. In physics, PACS is widely used. Gradually, digital library support for ETDs will support browsing using both broad schemes like DDC, as well as narrow schemes like PACS, integrated synergistically.
Next Section: Well known sites and resources for ETDs